Steam power plant for a marine vessel

ABSTRACT

The power plant includes one turbine having high and low pressure stages for driving the propeller screw during ahead travel and a second turbine for driving the propeller screw during astern travel. In addition, a reheater is interposed between the two stages of the first turbine. Bypass means are included to direct the generated steam around the first turbine to the second turbine for astern travel while also passing the steam through the reheater. During bypass, the steam can be throttled and cooled before passing into the reheater.

United States Patent [191 Dolezal 1 5] June 4, 1974 [54] STEAM POWER PLANT FOR A MARINE 3,361,108 1/1968 Hobbs .(60/102 x VESSEL 3,405,676 10/1968 Hobbs et al... 60/102 x [75] Inventor: Richard Joseph Dolezal, Winterthur, I Primary Examiner Edgar Geoghegan Swltzerland Assistan! Examiner-Allen M. Ostrager [73] Assignee: Sulzer Brothers Ltd., Winterthur, Attorney. 8? 0r "y & Kenyon y Switzerland Carr & Chapm [22] Filed: Feb. 1, 1973 [57] ABSTRACT [21] PP N05 328,671 The power plant includes one turbine having high and low pressure stages for driving the propeller screw [30] Forelgn Apphcfmon Pnomy Data during ahead travel and a second turbine for driving Feb. 3, Switzerland H}. the propeller screw during astern travel In addition a [52] US. Cl. 60/102, 60/73 7 reheater is interposed between the two stages of the [5|] Int. Cl. F0lk 7/00 first turbine. Bypass means are included to direct the [58] Field of Search 60/102 generated steam around the first turbine'to the second turbine for astern travel while also passing the steam [56] References Cited through the reheater. During bypass, the steam can be UNITED ES PATENTS v throttled and cooled before passing into the reheater. 2,855,756 10/1958 Hayden et al 60/102 10 Claims, 2 Drawing Figures 3283,5015 11/1966 Hutchinson et ali.. 60/102 3,295,320 l/l967 Takeda et all 60/l02 X STEAM POWER PLANT F OR A MARINE VESSEL This invention relates to a steam power plant for a marine vessel and particularly to a power plant for driving a marine vessel ahead or astern.

Briefly, the invention provides a steam power plant for driving a propulsion screw of a marine vessel so that the vessel can be driven ahead or astern. The power plant includes a steam generator of any suitable construction, a first turbine such as a multi-stage turbine drivingly connected to the screw for rotating the screw in a direction to propel the vessel ahead, and a second turbine also drivingly connected to the screw for rotating the screw in a direction to propel the vessel astern. In addition, a reheater is interposed between the stages of the first turbine to reheat the steam passing between the stages. The reheater is also connected at an exit to the second turbine to deliver steam thereto when the need arises. To this end, valve means are also provided in the power plant for selectively shutting off the flow of steam to the second turbine during ahead travel and for selectively shutting off the flow of steam to the first turbine during astern travel. This valve means cooperates with a bypass means for directing the generated flow of steam around the stages of the first turbine while passing through the reheater to the second turbine. A suitable means is also provided in the bypass means for thorttling and cooling the bypass steam upstream of the reheater.

The multi-stage turbine is constructed with an initial high-pressure stage and a final low-pressure stage with the reheater being connected between these two stages to conduct the flow of steam therebetween.

The steam power plant permits the second turbine, that is, the turbine for astern travel to be constructed as a low-pressure turbine. Thus, this turbine can be of low-cost construction. in addition, good cooling'of the reheater is achieved at all times, even when changing over from ahead travel to astern travel and vice versa, because the second turbine is connected to the exit of the reheater.

Further, the provision of a means to throttle and cool the steam in the bypass upstream of the reheater enables an additional amount of steam to be generated so that a high output is obtained, even in astern travel. Also, the means for throttling and cooling the steam may be in operation when the vessel is in port so that large quantities of low-pressure steam may be generated for heating purposes.

The valve means for selectively shutting off the flow of steam to the respective turbines includes valves for each of the stages of the first turbine and a valve for the second turbine. These valves are interlinked with respect to each other and so controlled so that as the valves for the stages of the first turbine open, the valve for the second turbine closes, and vice versa. In addition, these valves, in one embodiment, can be interlocked in overriding relation so that, for example, steam can be supplied forheating purposes during slow ahead travel. Also, in another embodiment, the valves for the turbines can be interlinked in a torque-balanced fashion so that if both turbines are operating, for example, at startup, the torques of the two turbines on the screw shaft balance each other.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 diagrammatically illustrates a steam power plant according to the invention; and

FIG. 2 diagrammatically illustrates a valve operating means with torque control utilized in a power plant according to the invention.

Referring to FIG. 1, the steam power propulsion plant is mounted in a ship or other suitable marine vessel and comprises a steam generator 1 with a superheater 2, a high-pressure turbine stage 4, a reheater 5, a low-pressure turbine stage 7, and a second turbine 20. The turbine stages 4 and 7 form a turbine for ahead travel and the second turbine 20 is for astern travel. The two turbines 4, 7 and 20 are connected to a ships propulsion screw 8 through a transmission (not shown). The low-pressure stage 7 and the second turbine 20 are connected in parallel to a condenser 10 which communicates via a condensate pump 11, a feed water tank 12 and a feed pump 13 with the steam generator l.

A valve means which includes valves 3, 6, 21, respectively, are disposed upstream of the entry of each of the two stages 4, 7 and of the second turbine 20 to enable the associated stage or turbine to be selectively started or shut off. The valve means cooperates with a bypass means which includes a duct 25 for bypassing the valve 3 and the high-pressure stage 4 and a device 26 in the duct 25 by means of which steam emerging from the superheater 2 may be throttled and cooled. To this end, a line 28 is branched off from the feed duct between the feed pump 13 and the steam generator 1 to supply feed water to the device 26 via a valve 27 for adjusting the water flow rate. The water is injected into the steam flow in the device 26 to cool the steam. The device 26 also contains a reducing valve for throttling the steam. The bypass means also includes a duct 31 which branches from the exit of the reheater 5 to which the low-pressure stage 7 and the second turbine 20 are connected, via the valves 6, 21, respectively. This duct 31 leads to various heat loads 30 of the kind conventional on ships and includes a valve 32 for controlling the flow of steam to these loads 30.

In ahead travel of the ship, the reducing valve in the device 26 and the valves 27, and 21 are closed and the valves 3 and 6 are opened. Steam will therefore flow from the generator 1 through the superheater 2 into the high-pressure stage 4 and become partially expanded. The steam is thereafter superheated again in the reheater 5, further expanded in the low-pressure stage 7 and finally condensed in the condenser 10. The condensate is then returned to the steam generator 1 via the condensate pump 11, the feed water tank 12 and the feed pump 13.

In astern travel, the valves 3 and 6 are closed and the pressure reducing valve'in the device 26 as well as the valves 27 and 21 are open. Steam will then flow from the generator 1 through the superheater 2 via the duct 25 into the device 26 where the pressure and temperature of the steam is reduced. The steam then passes via the reheater 5 to the second turbine 20 which drives the ships screw 8 in the direction opposite to that in which the screw 8 was previously driven by the first turbine 4, 7. The steam which is expanded in the turbine 20 is condensed in the condenser 10 and is then also returned to the steam generator 1. Good cooling of the reheater 5 is thus ensured even in astern travel.

When the shop is in port, the steam loads 3t may be supplied with steam via the device 26 and the reheater 5 while the turbines 4, 7 and are shut down via a closing of the valves 3, 6, 21.

As may be seen by the broken lines which extend to the reducing valve in the device 26 and the valves 3, 26, 6 and 21 and the plus and minus symbols, the valves are interlinked with respect to each other so that the above mentioned positions of the valves are obtained in ahead travel and astern travel respectively. The valves are actuated from a suitable control stand 50 in any suitable manner.

The interlinking of the valves may be at least partially over-ridden. For example, in slow ahead travel, that is when the valve 3 is partially open, the reducing valve in the device 26 and the valve 27 may be opened so that additional throttled steam may be supplied to the steam loads 30. In this operating state, it is possible for the valve 6 to be moved into the restricted position or to be entirely closed so that the high-pressure stage 4 predominantly or solely supplies the driving power.

lnterlinking ofthe valves 3, 6 and 211 may also be cancelled when the steam generator is started up or immediately prior to departure ofthe ship. in this case, steam may be simultaneously supplied to the turbine stages 4 and 7 and to the second turbine 20, either to heat up the two turbines and the pipelines or to increase the load on the steam generator. To this end, the valves must be adjusted so that the torque due to stages 4 and 7 and the torque due to the turbine 20 cancel each other.

Referring to FIG. 2, in order to adjust the valves 3, 6, 21 for a balanced-torque on the shaft of the screw,

a sensing means responsive to the rotation of the screw and a regulating means responsive to the sensing means are provided. The regulating means, in turn, is connected to the valves 3, 6, 21 so as to adjust the valves in opposite relation to each other. As shown, a toothed disc 40 is mounted on the screw shaft to rotate with the shaft. The sensing means includes a locking pawl 41 which may be selectively lowered by means of a servomotor 42 into the gaps between the teeth of the disc 40. The pawl 41 is guided by means of a slot 43 on a bolt 44 connected with the servomotor 42 so as to pivot about the bolt 44 should the pawl 41 be deflected by the disc. The sensing means also includes springs 45 disposed on opposite sides of the pawl 41 near the lower end thereof which abut against two parallel guide walls 48 secured on the pawl 41 to bias the pawl 41 into a middle position. The regulating means includes a rocker lever 47 which is pivotally mounted on a bolt 46 fixedly mounted in front of the pawl 41 as viewed. The rocker lever 47 has one downwardly orientated arm extending between the two-parallel guide walls 48 while a second arm forms a tapping of a potentiometer 49. In addition, a servomotor 5l which converts a rotary motion into an axial motion through a rod 52 is electrically connected to the potentiometer to receive a voltage. The rod 52 is, in turn, connected to one arm of a threearmed lever 53 while operating rods for the valves 3 and 6 on one side and for the valve 21 on the other side are connected to the two other arms of the lever '53. A

When the steam generator is started up or immedi ately prior to the departure of the vessel and when the valves 3, 6 and 21 are simultaneously opened so that steam is supplied to both turbines 4, 7 and 20, the locking pawl 41 is inserted by means of the servomotor 42 into a tooth gap of the disc 40 as indicated in FIG. 2. When the amounts of steam which flow into the turbines 4, 7 and 20 are so different as to produce a larger torque in one direction on the ships screw (not shown), the locking pawl 41 will be deflected about the bolt 44 slightly to the right or to the left. This deflection results in pivoting of the rocker lever 47 and therefore results in a change of the voltage which is tapped ofi from the potentiometer 49. According to this voltage change, the motor 51 is actuated so as to move the rod 52. The three-armed lever 53 is thus pivoted about the pivoting point of the servomotor rod 54 either in the clockwise or in the counterclockwise direction so that the valves 3 and 6 on the one side and the valve 21 on the other side are actuated in opposite senses. The amounts of steam which flow into the turbines 4, 7 and 20 are thus adjusted such that the magnitudes of both torques become equal and the pawl 41 returns to its middle position. After completion of the starting-up procedure of the steam generator or when the vessel departs, the pawl 41 is disengaged from the disc 40 by means of the servomotor 42.

What is claimed is:

H. In a marine vessel, a steam power plant for driving a propulsion screw of said vessel, said power plant comprising a steam generator for supplying steam;

a first turbine having a high-pressure stage and a lowpressure stage connected to said steam generator to receive steam and drivingly connected to said screw for rotating said screw to propel said vessel ahead;

a second turbine drivingly connected to said screw for rotating said screw to propel said vessel astern;

a reheater interposed between said stages of said first turbine for passage of a flow of steam from said first stage to said second stage, said reheater having an exit connected to said second turbine to deliver steam thereto;

valve means for selectively shutting off the flow of steam to said second turbine during ahead travel and for selectively shutting off the flow of steam to said first turbine during astern travel;

a bypass means for directing the flow of steam from said steam generator around said stages of said first turbine while passing through said reheater to said second turbine; and

means in said bypass means for throttling and cooling the bypassed steam upstream of said reheater.

2. The combination as set forth in claim 1 wherein said means in said bypass means includes a line for injecting feed water into the bypassed steam for cooling rod 54 of a servomotor 55, influenced by a signal from 6 the control stand 50 (not shown), is hinged in the middle of the levers 53 between the operating rods to the valves 3, 6 and 21.

the steam and a valve in said line for controlling the amount of feed water injected into the bypassed steam.

3. The combination as set forth in claim 1 wherein said valve means includes a first valve upstream of said high pressure stage, a second valve upstream of said low pressure stage and a third valve upstream of said second turbine.

4. The combination as set forth in claim 3 which further comprises means connecting said first and second valves in interlocked overriding relation to said third valve.

5. The combination as set forth in claim 3 which further comprises sensing means responsive to the rotation of said screw and a regulating means responsive to said sensing means for adjusting said first and second valves and said third valve in opposite relation to each other.

6. The combination as set forth in claim 5 wherein said sensing means includes an element mounted for selective movement into a predetermined position for deflection in response to the direction of rotation of said screw, and means responsive to deflection of said element for adjusting said valves.

7. The combination as set forth in claim 6 which further comprises a rotatable transmission shaft mounting said screw thereon and a ring fixed on said shaft having a plurality of projections extending therefrom, said ele ment being positioned between a pair of said projections.

8. in a marine vessel having a propulsion screw, a steam power for driving said screw, said steam power plant including a first turbine for rotating said screw in one direction;

a second turbine for rotating said screw in an opposite direction to said one direction; a reheater between said turbines; valve means for selectively shutting off a flow of steam to said second turbine during rotation of said screw in said one direction and for selectively shutting off a flow of steam to said first turbine during rotation of said screw in said opposite direction; and

bypass means for directing a flow of steam around said first turbine while passing through said reheater to said second turbine.

9. In a marine vessel as set forth in claim 8, said steam power plant further including means in said bypass means for throttling and cooling the bypassed steam upstream of said reheater.

10. In a marine vessel as set forth in claim 8 wherein said first turbine includes an initial high-pressure stage and a low-pressure stage with said reheater interposed between said stages and said second turbine is a lowpressure turbine. 

1. In a marine vessel, a steam power plant for driving a propulsion screw of said vessel, said power plant comprising a steam generator for supplying steam; a first turbine having a high-pressure stage and a low-pressure stage connected to said steam generator to receive steam and drivingly connected to said screw for rotating said screw to propel said vessel ahead; a second turbine drivingly connected to said screw for rotating said screw to propel said vessel astern; a reheater interposed between said stages of said first turbine for passage of a flow of steam from said first stage to said second stage, said reheater having an exit connected to said second turbine to deliver steam thereto; valve means for selectively shutting off the flow of steam to said second turbine during ahead travel and for selectively shutting off the flow of steam to said first turbine during astern travel; a bypass means for directing the flow of steam from said steam generator around said stages of said first turbine while passing through said reheater to said second turbine; and means in said bypass means for throttling and cooling the bypassed steam upstream of said reheater.
 2. The combination as set forth in claim 1 wherein said means in said bypass means includes a line for injecting feed water into the bypassed steam for cooling the steam and a valve in said line for controlling the amount of feed water injected into the bypassed steam.
 3. The combination as set forth in claim 1 wherein said valve means includes a first valve upstream of said high pressure stage, a second valve upstream of said low pressure stage and a third valve upstream of said second turbine.
 4. The combination as set forth in claim 3 which further comprises means connecting said first and second valves in interlocked overriding relation to said third valve.
 5. The combination as set forth in claim 3 which further comprises sensing means responsive to the rotation of said screw and a regulating means responsive to said sensing means for adjusting said first and second valves and said third valve in opposite relation to each other.
 6. The combination as set forth in claim 5 wherein said sensing means includes an element mounted for selective movement into a predetermined position for deflection in response to the direction of rotation of said screw, and means responsive to deflection of said element for adjusting said valves.
 7. The combination as set forth in claim 6 which further comprises a rotatable transmission shaft mounting said screw thereon and a ring fixed on said shaft having a plurality of projections extending therefrom, said element being positioned between a pair of said projections.
 8. In a marine vessel having a propulsion screw, a steam power for driving said screw, said steam power plant including a first turbine for rotating said screw in one direction; a second turbine for rotating said screw in an opposite direction to said one direction; a reheater between said turbines; valve mEans for selectively shutting off a flow of steam to said second turbine during rotation of said screw in said one direction and for selectively shutting off a flow of steam to said first turbine during rotation of said screw in said opposite direction; and bypass means for directing a flow of steam around said first turbine while passing through said reheater to said second turbine.
 9. In a marine vessel as set forth in claim 8, said steam power plant further including means in said bypass means for throttling and cooling the bypassed steam upstream of said reheater.
 10. In a marine vessel as set forth in claim 8 wherein said first turbine includes an initial high-pressure stage and a low-pressure stage with said reheater interposed between said stages and said second turbine is a low-pressure turbine. 